Well, the problem is this. First of all, she's an otaku through and through, she clearly doesn't see the vast majority of men that way which is why she 'falls' for 2D men. Secondly, she's an adult who is the school nurse and the MC is just a middle school kid (1st year I think?) so that's both a large age gap as well as a gap in 'social standing'. Third, the MC is more "comrade she can confide in" than love interest in the first place... then while the MC does think that she is very attractive, I don't remember him admitting that he likes her or anything.